1. Field of the Invention
The present invention relates to methods for fabricating a liquid crystal display (LCD) devices. More particularly the present invention relates to a method for fabricating an LCD while implementing a Multi-Model on Glass (MMG) technique with improved productivity.
2. Discussion of the Related Art
As information technology continues to evolve, the demand for, and development of, various types of flat panel display devices (e.g., liquid crystal display (LCD), plasma display panel (PDP), electroluminescent display (ELD), and vacuum fluorescent display (VFD)) increases. Among the various types of flat panel display devices, LCD devices are advantageously lightweight, dimensionally compact, consume relatively low amounts of power in their operation, display images at high resolution and high luminance, and can display images on a large-sized screen. Accordingly, LCD devices are widely used, for example, as substitutes for Cathode Ray Tubes (CRTs) and find numerous applications in mobile devices as such notebook computers, portable telephones, and the like, as well as in other applications such as televisions and computer monitors.
A typical LCD device includes an LCD panel for displaying images and a driver for supplying driving signals to the LCD panel. The LCD panel generally includes first and second substrates bonded to, but spaced apart from, each to form a gap therebetween. The first and second substrates are bonded together by a sealant material and a substantially uniform gap is maintained between the bonded substrates by the presence of spacers. A liquid crystal layer is formed within the gap between the first and second substrates by injecting liquid crystal material through an injection hole formed in the sealant material and into the gap.
FIG. 1 illustrates an exploded perspective view of a related art LCD panel.
Referring to FIG. 1, the related art LCD panel typically includes a lower substrate 1 bonded to an upper substrate 2 so as to maintain a gap therebetween. A liquid crystal layer 3 fills the gap between the lower and upper substrates 1 and 2.
The lower substrate 1 supports a plurality of gate lines 4 spaced apart from each other at a fixed interval and extending along a first direction; a plurality of data lines 5 spaced apart from each other at a fixed interval and extending along a second direction, substantially perpendicular to the first direction, to define a plurality of pixel regions ‘P’ arranged in a matrix pattern; pixel electrodes 6 formed in each of the pixel regions ‘P’; and thin film transistors ‘T’ at crossings of the gate and data lines 4 and 5.
The upper substrate 2 supports a black matrix layer 7 that prevents light from being transmitted in regions corresponding to the pixel regions ‘P’ of the lower substrate 1; R, G, B color filter layers 8 that selectively transmit predetermined wavelengths of light; and a common electrode 9 that enables images to be produced.
Generally, each thin film transistor ‘T’ includes a gate electrode that projects from a corresponding gate line 4, a gate insulating film (not shown) on the gate electrode, an active layer (not shown) on the gate insulating film and over the gate electrode, a source electrode that projects from a corresponding data line, and a drain electrode opposing the source electrode. Typically, the pixel electrode 6 is formed of a suitably transparent conductive metal such as indium-tin-oxide (ITO).
Upon applying predetermined voltages to the pixel and common electrodes of the LCD panel described above, an electric field, vertically oriented with respect to the lower and upper substrates, is generated to alter an arrangement of liquid crystal molecules within the liquid crystal layer 3. Upon altering the arrangement of liquid crystal molecules, light transmittance characteristics of the LCD panel are selectively altered and an image can thus be expressed. The LCD panel described above has good light transmissivity characteristics and a suitable aperture ratio. Further, the common electrode 9, supported by the upper substrate 2, serves as a grounding structure that prevents damage to liquid crystal cells caused by static electricity.
A method for fabricating the related art LCD panel shown in FIG. 1 will now be described in greater detail with reference to FIGS. 2 and 3. FIG. 2 illustrates a plan view of related art first and second model LCD panels and FIG. 3 illustrates a cross-sectional view of the LCD panel across a line II–II′ as shown in FIG. 2.
Referring generally to FIG. 2, a plurality of first and second LCD panel models 20 and 30, respectively, are formed on the same first and second base substrates 21 and 31, respectively. Other than their differences in panel size, the first LCD panel models 20 are essentially identical as the second LCD panel models 30 because both the first and second LCD panel models 20 and 30 are fabricated by performing the same fabrication processes (e.g., film deposition, photolithography, etc.) on the first and second substrates 21 and 31.
Thus, the second substrate 31 supports a plurality of gate lines spaced apart from each other at a fixed interval and extending along a first direction; a plurality of data lines spaced apart from each other and extending along a second direction, substantially perpendicular to the first direction, to define a plurality of pixel regions arranged in a matrix pattern; a plurality of pixel electrodes within the pixel regions; and a plurality of thin film transistors switching signals from the data lines to corresponding pixel electrodes in response to signals transmitted by corresponding gate lines.
The first substrate 21 supports a black matrix layer that prevents light from being transmitted outside areas corresponding to the pixel regions of the second substrate 1; R, G, B color filter layers that selectively transmit predetermined wavelengths of light; and a common electrode that enables images to be produced. In-Plane Switching (IPS)-type LCD panels, however, may be provided with the common electrode formed on the second substrate 31.
Referring still to FIG. 3, the aforementioned first and second substrates 21 and 31 are bonded to each other via a sealant material and a substantially uniform gap is maintained between the bonded substrates by a plurality of spacers. Accordingly, the first LCD panel models 20 include the first spacers 23 while the second LCD panel models 30 include the second spacers 33. As shown, the height of the first spacers 23 for the first LCD panel models 20 is equal to the height of the second spacers 33 for the second LCD panel models 30. Moreover, the thickness of the first color filter layers 22 of the first LCD panel models 20 is equal to the thickness of the second color filter layers 32 of the second LCD panel models 30.
As described above, the same base substrates can beneficially be used to form multiple LCD panel models (hereinafter referred to as “Multi-Model on Glass”, or “MMG”, technique) with varying panel sizes. Because the various LCD panels models must be fabricated using the same processes, however, it is almost impossible to implement the MMG technique while varying LCD panel characteristics other than panel size. Accordingly, implementation of related art MMG techniques can be extremely limited in scope.